1. Field of the Invention
The present invention relates to an image forming apparatus capable of forming images by using a toner replenishing unit for supplying toner to either or both of a process cartridge and a developing cartridge in the image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.
2. Related Background Art
Conventional electrophotographic image forming apparatuses have been adopting a process cartridge system in which a photosensitive body, charging or electrifying means, developing means, cleaning means, a toner container unit and the like are integrated into a cartridge. In this system, the cartridge is removably attached in the main body of the image forming apparatus concerned.
Such a cartridge system makes operation easier, and enables users themselves to do maintenance work on the process means. For these reasons, this type of cartridge system has been widely employed in the main bodies of the conventional image forming apparatuses.
Another type of cartridge configuration that can be used depending upon the life of the main process means has also been achieved, in which the process means is divided into long- and short-life groups and each group is integrated into a cartridge.
For example, a developing cartridge with a toner container or containers and developing means formed together therein, and a drum cartridge with an electrophotographic photosensitive body, charging means and cleaning means formed together therein have been adopted.
Recently, due to growth in demand for color electrophotographic image forming apparatuses capable of forming color images, expectations have been running for satisfaction of the following seven items: (a) low running cost, (b) small installation space, (c) low power consumption, (d) high quality, (e) high speed, (f) improved usability, and (g) ecology.
Conventional types of process cartridges and developing cartridges need to be replaced with new ones as soon as the cartridges run out of toner, which causes the following problems.
(1) In many cases, the above-mentioned cartridges are collected and recycled in cartridge-manufacturers"" recycling systems or by private recycling dealers, but they may end up as waste.
It is therefore desirable to extend the life of the cartridges as long as possible, and hence to reduce the total amount of cartridge waste from environmental protection and resource saving standpoints. In other words, the life of the process means (such as an electrophotographic photosensitive body and a developing roller) and toner, both of which influence the life of the cartridge, need to be extended as long as possible.
In the event that the life of the process means is extended, an amount of toner corresponding to the life of the process means Is supposed to be contained in the cartridge. The total weight of toner would increase in proportion to the life of the process means.
If the process means has a life span of up to 50,000 image copies, a required amount of toner will weigh 1.25 to 1.5 kg. If such a large amount of toner is contained in the cartridge, the total weight and volume will be necessarily increased, which runs the danger of reducing the operability.
(2) The main body of the image forming apparatus also needs a frame structure that can precisely support such a heavy cartridge, which results in an increase in the price of the entire apparatus.
(3) Further, in conventional toner replenishing type dual-component developing systems, a hopper for toner storage is provided in the main body of the image forming apparatus. In this case, toner is supplied from a toner replenishing container to the hopper, and to a developing device in this order.
In such a configuration, toner in the hopper can be used even if the toner replenishing container runs out of toner, which allows for a certain delay in exchanging cartridges.
The mechanism of the hopper part, however, increases the total number of parts, and hence the size of the cartridge, which also results in reducing the operability and increasing the total cost.
On the other hand, the time delay in exchanging cartridges makes it difficult not only to know the exact time to exchange cartridges, but also to measure the exact amount of residual toner in the toner replenishing container. This might cause trouble or image degradation in the process of image formation at the end of the life of toner, that is, as the toner replenishing container is running out of toner. Such a difference in image quality becomes visible especially in the formation of color images.
Since vivid color images cannot be formed even though there remains unused toner in the toner replenishing container, the time the cartridge needs replacing is brought forward, which makes it hard to effectively utilize resources despite the extended life cycle of the cartridge.
It is therefore an object of the present invention to provide an image forming apparatus capable of precisely detecting the remaining amount of developer in an inexpensive, compact configuration so that the timing of replacing a developer replenishing container can be delayed to make the developer replenishing container last longer.
In one aspect of the present invention, there is provided an image forming apparatus that uses a removable developer replenishing unit to control the replenishment of developer from the developer replenishing unit to an electrophotographic image forming body part so as to form images, the developer replenishing unit including a first storage for storing identification information related to identities of the developer and a second storage for storing history information related to the developer, the apparatus comprising: an information comparing means that reads out the identification information from the developer replenishing unit and compares the read-out identification information with unique information stored in the image forming body part to determine whether both pieces of information accord; a life judgment means that reads out the history information from the developer replenishing unit when the comparison result shows that both pieces of information accord, and analyzes the read-out history information to judge whether the utilization amount of the developer replenishing unit is at the end of its useful life; and an image forming control means that performs control of image formation when the judgment result shows that the utilization amount is not at the end of its useful life, by controlling the discharge amount of the developer replenished from the developer replenishing unit according to the read-out history information and image output information from the image forming body part.
The image forming control means may include a detection means for detecting image output information related to the density of an image formed in the image forming body part, a comparison means for comparing the detected image output information with a reference value to determine whether the image density is lower than the reference value, and a discharge controlling means for controlling the discharge amount of the developer discharged from the developer replenishing unit when the comparison result shows that the image density is lower than the reference value.
The discharge controlling means may include a feed amount deciding means for deciding the feed amount of the developer replenishing unit on the basis of the image output information detected, and a variable power control means for controlling the discharge amount of the developer by multiplying the decided feed amount by certain number varied according to the amount of the developer remaining in the developer replenishing unit.
The image forming apparatus may also comprise a utilization amount calculating means for calculating the utilization amount of the developer in the developer replenishing unit on the basis of the decided feed amount.
The image forming apparatus may further comprise a means for calculating, from the utilization amount calculated, the total amount of the developer consumed in the developer replenishing unit, and storing the total consumed amount into the second storage of the developer replenishing unit as the history information.
The history information stored in the second storage may contain threshold data indicative of the life of the developer replenishing unit for stopping the operation of the image forming body part, or threshold data for informing the user of the level of life span of the developer replenishing unit.
The history information stored in the second storage may also contain driving control threshold data indicative of the timing of multiplying the driving amount of the developer replenishing unit by a certain number, and data indicative of a coefficient for multiplying the driving amount of the developer replenishing unit by the certain number.
The history information stored in the second storage may further contain correction constants for use in calculating the amount of the developer consumed.
The correction constants stored in the second storage may include one or more of the following correction constants: a developer correction constant based on the kind of developer of the developer replenishing unit, a humidity correction constant based on variations in humidity of the developer, a utilization amount correction constant based on the utilization amount of the developer replenishing unit, a driving amount correction constant based on the driving amount of the developer replenishing unit, and a part history correction constant based on the parts constituting the developer replenishing unit.
The developer replenishing unit may perform the i-th cycle of replenishment such that a driving amount N of the developer replenishing unit is determined every time on the basis of output voltage from a developer density detecting means arranged in the image forming body part to make the developer replenishing unit feed the developer by the amount N, while a utilization amount xcex94X is calculated from the driving amount N or an actual driving amount Nxe2x80x2 and the correction constants stored in the first storage of the developer replenishing unit to determine the total utilization amount X up to the i-th cycle as X=X+xcex94X so as to store the total utilization amount X into the second storage of the developer replenishing unit before starting the next cycle of replenishment.
The developer replenishing unit may also perform replenishing operation such that a driving amount N of the developer replenishing unit is determined on the basis of output voltage from the developer density detecting means to control the driving of the developer replenishing unit by taking one turn as a unit to be repeated according to the driving amount N.
In another aspect of the present invention, there is provided an image forming method for forming images by using a removable developer replenishing unit and controlling the replenishment of developer from the developer replenishing unit to an electrophotographic image forming body part, the developer replenishing unit including a first storage for storing identification information related to identities of the developer and a second storage for storing history information related to the developer, the method comprising: an information comparing step of reading out the identification information from the developer replenishing unit and comparing the read-out identification information with unique information stored in the image forming body part to determine whether both pieces of information accord; a life judgment step in which when the comparison result shows that both pieces of information accord, the history information is read out from the developer replenishing unit and the read-out history information is analyzed to judge whether the utilization amount of the developer replenishing unit is at the end of its useful life; and an image forming control step in which when the judgment result shows that the utilization amount is not at the end of its useful life, image formation is controlled by controlling the discharge amount of the developer replenished from the developer replenishing unit according to the read-out history information and image output information from the image forming body part.
In still another aspect of the present invention, there is provided a medium with an image forming control program recorded thereon, the program instructing a computer to control the replenishment of developer from a removable developer replenishing unit to an electrophotographic image forming body part during image formation, the developer replenishing unit including a first storage for storing identification information related to identities of the developer and a second storage for storing history information related to the developer, the control program comprising the steps of: instructing the computer to read out the identification information from the developer replenishing unit and compare the read-out identification information with unique information stored in the image forming body part to determine whether both pieces of information accord; instructing the computer to read out the history information from the developer replenishing unit when the comparison result shows that both pieces of information accord, and analyze the read-out history information so as to judge whether the utilization amount of the developer replenishing unit is at the end of its useful life; and instructing the computer to control image formation when the judgment result shows that the utilization amount is not at the end of its useful life, by controlling the discharge amount of the developer replenished from the developer replenishing unit according to the read-out history information and image output information from the image forming body part.
In yet another aspect of the present invention, there is provided an image forming apparatus that uses a removable recording agent replenishing unit to control the replenishment of a recording agent from the recording agent replenishing unit to an electrophotographic image forming body part so as to form images, the recording agent replenishing unit including a first storage for storing identification information related to identities of the recording agent and a second storage for storing history information related to the recording agent, the apparatus comprising: an information comparing means that reads out the identification information from the recording agent replenishing unit and compares the read-out identification information with unique information stored in the image forming body part to determine whether both pieces of information accord; a life judgment means that reads out the history information from the recording agent replenishing unit when the comparison result shows that both pieces of information accord, and analyzes the read-out history information to judge whether the utilization amount of the recording agent replenishing unit is at the end of its useful life; and an image forming control means that performs control of image formation when the judgment result shows that the utilization amount is not at the end of its useful life, by controlling the discharge amount of the recording agent replenished from the recording agent replenishing unit according to the read-out history information and image output information from the image forming body part.
The image forming control means may include a detection means for detecting image output information related to the density of an image formed in the image forming body part, a comparison means for comparing the detected image output information with a reference value to determine whether the image density is lower than the reference value, and a discharge controlling means for controlling the discharge amount of the recording agent discharged from the recording agent replenishing unit when the comparison result shows that the image density is lower than the reference value.
The discharge controlling means may include a feed amount deciding means for deciding the feed amount of the recording agent replenishing unit on the basis of the image output information detected, and a variable power control means for controlling the discharge amount of the recording agent by multiplying the decided feed amount by a certain number varied according to the amount of the recording agent remaining in the recording agent replenishing unit.
The image forming apparatus may also comprise a utilization amount calculating means for calculating the utilization amount of the recording agent in the recording agent replenishing unit on the basis of the decided feed amount.
The image forming apparatus may further comprise a means for calculating, from the utilization amount calculated, the total amount of the recording agent consumed in the recording agent replenishing unit, and storing the total consumed amount into the second storage of the recording agent replenishing unit as the history information.
In still another aspect of the present invention, there is provided an image forming method for forming images by using a removable recording agent replenishing unit and controlling the replenishment of a recording agent from the recording agent replenishing unit to an electrophotographic image forming body part, the recording agent replenishing unit including a first storage for storing identification information related to identities of the recording agent and a second storage for storing history information related to the recording agent, the method comprising: an information comparing step of reading out the identification information from the recording agent replenishing unit and comparing the read-out identification information with unique information stored in the image forming body part to determine whether both pieces of information accord; a life judgment step in which when the comparison result shows that both pieces of information accord, the history information is read out from the recording agent replenishing unit and the read-out history information is analyzed to judge whether the utilization amount of the recording agent replenishing unit is at the end of its useful life; and an image forming control step in which when the judgment result shows that the utilization amount is not at the end of its useful life, image formation is controlled by controlling the discharge amount of the recording agent replenished from the recording agent replenishing unit according to the read-out history information and image output information from the image forming body part.
In yet another aspect of the present invention, there is provided a medium with an image forming control program recorded thereon, the control program instructing a computer to control the replenishment of a recording agent from a removable recording agent replenishing unit to an electrophotographic image forming body part during image formation, the recording agent replenishing unit including a first storage for storing identification information related to identities of the recording agent and a second storage for storing history information related to the recording agent, the control program comprising the steps of: instructing the computer to read out the identification information from the recording agent replenishing unit and compare the read-out identification information with unique information stored in the image forming body part to determine whether both pieces of information accord; instructing the computer to read out the history information from the recording agent replenishing unit when the comparison result shows that both pieces of information accord, and analyze the read-out history information so as to judge whether the utilization amount of the recording agent replenishing unit is at the end of its useful life; and instructing the computer to control image formation when the judgment result shows that the utilization amount is not at the end of its useful life, by controlling the discharge amount of the recording agent replenished from the recording agent replenishing unit according to the read-out history information and image output information from the image forming body part.
According to the present invention, the image forming apparatus uses the developer replenishing unit that includes the first storage for storing identification information related to identities of developer and the second storage for storing history information related to the developer. The identification information is read out from the developer replenishing unit, and the read-out identification information is compared with unique information stored in the image forming body part to determine whether both pieces of information accord. If both accord, the history information is read out from the developer replenishing unit and the read-out history information is analyzed to judge whether the utilization amount of the developer replenishing unit is at the end of its useful life. If the utilization amount is not at the end of its useful life, the discharge amount of the developer replenished from the developer replenishing unit is controlled according to the read-out history information and image output information from the image forming body part. This configuration allows precise detection of the remaining amount of the developer, and hence further reduction on the amount of toner remaining in the developer replenishing unit. Consequently, stable replenishment of toner is possible even at the end of its useful life, which also makes it possible to delay the timing of replacing the developer replenishing container and hence to make the developer replenishing container last longer.
Further, according to the present invention, the amount of toner consumption can be estimated more precisely, so that the user can be informed more exactly when the developer replenishing unit needs replacing.
Furthermore, according to the present invention, the above-mentioned configuration does not need the hopper part as required in the conventional, which makes the entire apparatus inexpensive and compact.
Other objects and aspects of the present invention will become apparent from the following description of an embodiment with reference to the accompanying drawings.